JPS6058514B2 - coin sorting device - Google Patents

Description

Detailed Description of the Invention The present invention applies an alternating magnetic field to a coin to be tested, and detects changes in the amount and phase of overcurrent generated inside the coin due to its material or shape, and changes in magnetic permeability by detecting changes in the inductance of the detection coil. The present invention relates to a coin sorting device that determines the suitability of test coins based on the rate of change.

The sterilization coin sorting device determines suitability by comparing the reference inductance value for genuine coins stored in a memory or the like with the measured inductance value obtained from the test coin.

However, the inductance (hereinafter referred to as initial inductance) of the detection coil when no test coin is present is determined by the number of turns and winding shape of the winding, as well as the magnetic permeability of the core. Differences occur in the initial inductance of the detection coil.Therefore, in the case of genuine coins, the reference inductance value must be set according to the detection coil (that is, according to the coin sorting device), but the initial inductance depends on the operating conditions such as temperature. Considering that the reference inductance value varies due to changes in the value or changes over time, it is not necessarily effective to set a reference inductance value according to the detection coil during the manufacturing process of the coin sorting device. Therefore, when comparing the standard inductance value and the measured inductance value of the test coin, a wide tolerance range is set to eliminate variations in the initial inductance of the detection coil. However, it is unlikely that highly accurate coin sorting can be expected in this case.In addition, if the suitability is determined by taking the ratio or difference between the initial inductance value immediately before the coin is inserted and the measured inductance value, it is possible to detect changes in usage conditions or changes over time. Although it is possible to deal with variations in the initial inductance value, it does not eliminate the differences in initial inductance of individual detection coils during manufacturing, and the ratio or difference between the initial inductance value and the standard inductance value of genuine coins for each detection coil. In addition, when taking the ratio, a division circuit is required and is expensive, and when taking the difference, the error increases as the initial inductance value changes and the accuracy decreases. The present invention provides a coin sorting device that can add both the initial inductance difference during the manufacturing of the detection coil and the initial inductance variation due to usage conditions or changes over time to the coin suitability inspection parameters. There are things.

Figure 1 shows the inductance characteristics a.
... is a graph showing b.

As is clear from the figure, the initial inductance is always constant regardless of the frequency, but the inductance when a coin is present decreases as the frequency increases up to a certain frequency f1; It can be seen that it becomes constant after f1. Furthermore, Fig. 2 is a graph plotting the inductance change ΔL when a coin is present against the initial inductance value of various types of detection coils when an arbitrary frequency higher than f1 in Fig. 1 is applied to the detection coil. . From this figure, it can be seen that in a predetermined high frequency range, the inductance when a coin is present has a constant ratio to the initial inductance. This can be explained by the reasons described below. That is, as the frequency increases, the eddy current increases, and due to the phenomenon of the so-called skin effect, the magnetic flux can penetrate into the inside of the coin, which is no longer affected by the material of the coin, and the inductance change becomes constant. Although there are differences depending on the shape and characteristics of the detection coil, the first
It has been confirmed that f1 in the figure is around 200 KHz. In such a high frequency region, the skin depth (skin depth of magnetic flux) is extremely small relative to the thickness of the coin to be tested, which causes changes in inductance that are sensitive to the surface shape and outer diameter of the coin to be tested, making it difficult to sort this type of coin. The frequency that can be effectively used regarding the equipment. It can be said to be the wave number. Based on the above points, the present invention focuses on the fact that even if the initial inductance fluctuates during inspection using a high-frequency magnetic field, the inductance due to the insertion of a coin to be tested will change according to the variation, and if the initial inductance fluctuates - The purpose of this method is to correct the measurement conditions according to the amount of time and obtain the measured inductance value under the same conditions as the reference inductance value.

An embodiment of the present invention will be described in detail below with reference to the drawings.

Incidentally, a change in inductance can be captured by the balance by a bridge circuit, a phase change, and a change in oscillation frequency, but in this embodiment, the inductance is captured by the value of the oscillation frequency. FIG. 3 shows an inductance detector, in which a detection coil 9 forming the inductance of the oscillation circuit 1 is wound around an REJ-shaped core 7, and is arranged in relation to the coin path 8 so that the magnetic field is perpendicular to the surface of the test coin 6. has been done.
In FIG. 4, the oscillation pulse output from the oscillation circuit 1 is input to the frequency divider circuit 2, and the oscillation frequency is counted. AND gate 1 together with reference oscillator 11 via
2, and the AND gate 12 is further connected to a reversible counter. The reversible counting device 11 is an addition counter 1
4 and a subtraction counter 15, output terminals Q1...Qn of each counting stage of the addition counter 14 are connected to input terminals D1 to Dn of each counting stage of the subtraction counter 15. Output terminal Q1 of each counting stage of the subtraction counter 15
.
A reference oscillation frequency is set in the reference value storage device 4, and the oscillation frequency counted by the counting circuit 3 is compared with the reference oscillation frequency of the coincidence detection circuit 5 to determine the suitability of the test coin. The sequence control circuit 18 receives the status signal cm
The control signals a, b, d, e, f, and g are set to RH (high level) or RLJ (low level) by inputting d and h, respectively.
It controls the operations of the frequency divider circuit 2, the reversible counting device ± rise/coincidence detection circuit 5, and the AND gates 17 and 19. That is, the sequence control circuit 18 receives the status signal cm
The frequency divider circuit 2, reversible counter 11, coincidence detection circuit 5, AND gate 17 and
9 operating procedures are set. The operation will be explained along the time chart shown in FIG.

First, during the initial reset period, the sequence control unit 18 outputs RHJ to the control signal b to control the frequency dividing circuit 2 and addition counter 1.
Reset 4. In the next measurement time determination period, the sequence control unit 18 outputs RHJ to the control signals ae, respectively, and makes the AND gates 19 and 12 conductive.

At this time, the frequency dividing circuit 2 has been reset and the status signal c is RLJ, but since RH is input to the AND gate 12 by the inverter 10, the clock pulse generated in the reference oscillator 11 is introduced into the addition counter 14. is counted. Further, the oscillation pulse generated from the oscillation circuit 1 according to the initial inductance of the detection coil 9 is generated by the AND gate 19.
is introduced into the frequency divider circuit 2 via the frequency divider circuit 2 and counted. Frequency divider circuit 2
When the predetermined frequency division value N is counted, the RHJ status signal C
In response to input of this signal C, the sequence control unit 18 sets the control signals a to e to RL, respectively, and controls the AND gates 19 and 12 to be non-conductive. Therefore, the counting operations of the frequency dividing circuit 2 and the addition counter 14 are stopped, and the measurement time determination period ends. In this operation during the measurement time determination period, the time required for the frequency divider circuit 2 to count the above-mentioned predetermined value N, that is, the measurement time based on the initial inductance of the detection coil 9 depending on various conditions at the present time, is added. It is counted by the counter 14. During the reset period, the sequence control circuit 18 outputs RHJ as the control signal f, and this signal causes the subtraction counter 15 to preset the count value of the counter 14, and the counting circuit 3 is reset.

Next, the sequence control circuit 18 sets the control signal b to RHJ and resets the frequency divider circuit 2 and the addition counter 14.
Then, a status signal d indicating that the test coin 6 has been inserted is transmitted to a coin detector 20 disposed near the detection coil 9, for example.
When the signal is output from the subtraction counter 15, it becomes an inductance detection period in which the inductance (oscillation frequency) due to the test coin 6 is measured over the measurement time preset in the subtraction counter 15.

However, if the status signal d is not input within the time preset in the sequence control section 18, the sequence control section 18 again outputs RH to the control signal b to set the reset period, and then outputs the control signal a to the control signal a. RHJ is output to e and RLJ is output to control signal b, and a measurement time determination period begins.
Therefore, when no test coin is inserted, the best measurement time at that time is always detected every certain cycle and the value is preset in the subtraction counter 15. During the inductance detection period, the sequence control section 18 outputs RHJ to the control signal g, turns on the AND gate 21, and controls the clock pulse from the reference oscillator 11 to be introduced into the subtraction counter 15 to perform a subtraction counting operation.

The 0R gate 16 is R when an output is generated in any counting stage of the subtraction counter 15 (that is, the count content is not zero).
In order to output HJ, the 7VsJD gate 17 is made conductive by the control signal GrHJ, and the oscillation pulse generated by the oscillation circuit 1 due to the presence of the test coin is input to the counting circuit 3 and counted.

When the subtraction counter 15 becomes zero due to the subtraction, that is, when the preset measurement time elapses, the 0R gate 16
becomes RLJ, the AND gate 17 becomes non-conductive, and the counting operation of the counting circuit 3 stops. Therefore, counting circuit 3
The oscillation frequency is measured by counting oscillation pulses over a period of time preset in the subtraction counter 15.
When the output RLJ of the 0R gate 16 is inputted to the sequence control unit 18 as the status signal h, the inductance detection period ends and the inspection coin suitability determination period begins.

During the appropriateness determination period, the sequence control unit 18 outputs RHJ to the control signal 1 and instructs the coincidence detection circuit 5 to compare the oscillation frequency counted by the counting circuit 3 with the reference frequency set in the reference value storage device 4. .

If the oscillation frequency and the reference frequency match, or if they match within a tolerance range, the test coin is determined to be appropriate. The reference frequency is set in advance in the reference value storage device as follows. That is, after industrially producing such a coin sorting device, the ratio (f/FO) between the oscillation frequency FO due to the initial inductance of the oscillation circuit 1 and the oscillation frequency f due to the inductance in the presence of a typical genuine coin is determined by the frequency division value N.
The multiplied value is the reference frequency. Such reference value setting must be performed for the purpose of correcting the mechanical relative position between the detection coil 9 and the test coin 6 for each completed device, but this relative position can be configured with high precision. Since variations in the initial inductance of each detection coil 9 can be absorbed by the circuit, a typical reference frequency can be set commonly for each device. In addition, during the measurement time determination period, when the test coin 6 is inserted while the addition counter 14 is counting and the status signal d is input, the sequence control circuit 18 immediately changes the control signals ae to RLJ and the control signal g to RHJ and subtracts the current value. The value preset by the counter 15 is taken as the measurement time. That is, in such a situation, the measurement time obtained in the previous cycle is used as the measurement time for inductance detection of the test coin 6 inserted in the current cycle. According to the present invention described in detail above, in a coin sorting device that uses a high-frequency magnetic field in which the penetration of the magnetic flux into the surface of the coin is sufficiently small relative to the plate thickness of the coin to be inspected, initial conditions are measured and inspection is performed based on the initial conditions. The purpose is to improve the sorting accuracy by calibrating the inductance value obtained from the test coin by determining the measurement time when inserting the coin, and then comparing it with the reference inductance value for genuine coins.

Therefore, differences in the initial inductance of the detection coil for each device or variations in the initial inductance due to changes in usage conditions and changes over time can be absorbed into the circuit, and a decrease in sorting accuracy can be avoided. Furthermore, the reference inductance value can be uniformly set to a value obtained by multiplying the ratio of the initial inductance value of a typical device and the inductance value due to the presence of genuine coins by the frequency division value N, and the variation among detection coils can be eliminated using the circuit. It is possible to reduce costs by absorbing this.

[Brief explanation of drawings]

Figure 1 shows the frequency-inductance characteristics depending on the presence/absence of a test coin, Figure 2 shows the initial inductance change characteristics at an arbitrary frequency in the high frequency region, Figure 3 shows the inductance detector, and Figure 4 shows the inductance characteristics. The figure shows a circuit of the invention, and FIG. 5 shows a timing chart. 1... Oscillation circuit, 2... Frequency dividing circuit, 3
3... Counting circuit, 4... Reference value storage device, 5... Coincidence detection circuit.

Claims (1)

[Claims] 1. Means for forming a high-frequency magnetic field in which the skin penetration of magnetic flux is sufficiently small relative to the thickness of the test coin, and detecting the inductance of the means for forming the magnetic field and outputting an oscillation pulse with a width corresponding to the detected value. means for determining the measurement time by counting a predetermined number of the oscillation pulses when the test coin is not present; and means for determining the measurement time by counting the oscillation pulses by a predetermined number when the test coin is not present; means for counting and obtaining a measured inductance value; means for previously setting a reference inductance value for genuine coins; and means for comparing the measured inductance value with the reference inductance value to determine the suitability of the test coin. A coin sorting device consisting of.